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TJ transfer cases are fitment-critical. Match the ID tag, transmission input spline count and output arrangement before buying; standard TJs use NP231J while Rubicons use NP241OR.
| # | Product | Price | Where to buy |
|---|---|---|---|
| 1 | National Differential Remanufactured NP231J | $1,000–$1,800 | Amazon |
| 2 | The Gear Shop 231J Transfer Case | $795–$955 | Amazon |
| 3 | Novak NP231J Master Rebuild Kit | $200–$300 | Amazon |
| 4 | Novak NP231 Ultra-Short SYE Kit | $300–$450 | Amazon |
| 5 | JB Conversions NP231J Heavy Duty Slip Yoke Eliminator | $250–$400 | Amazon |
| 6 | NV241OR Rock-Trac Transfer Case | $1,500–$2,500 | Amazon · eBay |
| 7 | Teraflex NP231J 4:1 Low Range Kit | $900–$1,300 | Amazon |
| 8 | JB Conversions NP231J 4:1 Kit | $900–$1,400 | Amazon |
| 9 | Advance Adapters Atlas II Transfer Case | $3,000–$4,500 | Amazon |
The picks, in detail
National Differential Remanufactured NP231J
Remanufactured NP231J sold for 1997–2006 Jeep Wrangler TJ applications.
- remanufactured
- TJ application
- direct stock-family choice
- confirm splines
The Gear Shop 231J Transfer Case
Replacement 231J assembly listed for 1987–2006 Wrangler, including the TJ generation.
- 231J design
- rebuilt option
- specialist source
- verify year
Novak NP231J Master Rebuild Kit
Rebuild-kit route for retaining a compatible TJ NP231J rather than changing transfer-case families.
- master kit
- NP231J specific
- keeps original case
- requires rebuild work
Novak NP231 Ultra-Short SYE Kit
Slip-yoke-eliminator upgrade for a TJ NP231 build when a fixed rear output is needed.
- fixed-yoke conversion
- NP231 fitment
- supports driveshaft changes
- not a complete case
JB Conversions NP231J Heavy Duty Slip Yoke Eliminator
Heavy-duty SYE option for a compatible NP231J-based TJ transfer case.
- fixed yoke
- heavy-duty output
- trail-oriented upgrade
- install complexity
NV241OR Rock-Trac Transfer Case
Factory Rubicon TJ transfer case with 4.0:1 low range; it is for Rubicon-specific builds, not a direct standard-TJ replacement.
- 4.0 low range
- Rubicon equipment
- deep crawl ratio
- not direct swap
Teraflex NP231J 4:1 Low Range Kit
Teraflex 4:1 kit is an internal low-range upgrade for compatible TJ/LJ NP231J transfer cases.
- 4:1 low range
- NP231J fitment
- deeper crawl ratio
- internal installation
JB Conversions NP231J 4:1 Kit
JB Conversions offers a 4:1 low-range route for an NP231J build when the case and drivetrain are compatible.
- 4:1 gearing
- NP231J specific
- trail upgrade
- professional setup advised
Advance Adapters Atlas II Transfer Case
Atlas II is a heavy-duty aftermarket transfer-case option for purpose-built TJ drivetrain conversions.
- gear-driven
- multiple ratios
- serious off-road capability
- requires conversion planning
Buying tips
- Read the round tag on the case before ordering.
- Do not treat a Rubicon NV241OR as a direct NP231J substitute.
As an Amazon Associate and eBay Partner, toptenpick.com earns from qualifying purchases. Prices and availability are subject to change.